BRUNSWICK, Ga. (AP) — A Georgia man swapped sexual text messages with a teenage girl while his toddler son sat forgotten and dying in the back seat of the father’s sweltering SUV, his young texting partner testified in court Friday.

Justin Ross Harris, 34, is charged with murder in the death of his 22-month-old son, Cooper. He’s also charged with sending graphic, sexual text messages and photos of his penis to a girl for a period of several months when she was 16 and 17.

That young woman, now 19, told the jury Friday she met Harris online in the fall of 2013 when he responded to a comment she posted on the app Whisper stating she wanted a sexual relationship like the one depicted in the erotic novel “Fifty Shades of Grey.”

“When it started, it was strictly sexual,” the witness said of her relationship with Harris. “Then at times it would be like a normal conversation.”

They never met in person, but Harris knew her age and that she was in high school, the young woman testified. She sent him one of her prom photos, she said, and would tell him about her efforts to choose a college.

According to a transcript of their text messages that the young woman read in court, one time Harris asked for a photo of her breasts and she replied: “I’m at school.”

They also discussed sex acts they wanted to perform with each other, and Harris would send the girl photos of his penis. A prosecutor showed four photos to the jury in court. She said he asked her to send him photos of her genitals “countless” times, but she never did.

“There wasn’t any pressure applied to you to participate in this, is that fair to say,” defense attorney Maddox Kilgore asked the young woman.

“Yes,” she replied.

Prosecutor Chuck Boring noted that under Georgia law, the girl’s consent was irrelevant because she was a minor.

The Associated Press does not identify victims of sex crimes and is not identifying the young woman, who was underage when the explicit messages were sent. The judge also has barred news organizations from broadcasting her voice and likeness to protect her identity.

Prosecutors say Harris, who had moved to metro Atlanta from Alabama in 2012, killed his young son intentionally because he wanted to escape from the responsibilities of being a husband and father. The teenager wasn’t the only person he swapped sexual images and banter with online. Several women have testified to having sexual relationships with Harris, both online and in person, while he was married.

Authorities say Harris’ son died after being left strapped in his car seat for about seven hours while Harris was working at Home Depot’s headquarters in metro Atlanta. Harris had taken his son with him to eat breakfast that morning. His defense attorneys say the death was a tragic accident — that Harris forgot to drop the boy off at daycare and went straight to work.

The day young Cooper died on June 18, 2014, his father was texting the teenage girl from his workplace, according to transcripts read in court Friday.

At about 2 p.m. that day, he asked for a photo of her breasts.

“I’m super sunburned,” the witness read from the transcript in court, saying she sent a photo regardless.

Harris’ reply: “Yummy.”

Harris’ trial was moved from Cobb County in the Atlanta suburbs, to the coastal port city of Brunswick because of pretrial publicity. The judge told jurors Friday she expects the trial, which began Oct. 3, to last three to four more weeks.

The young woman said Harris would sometimes send her photographs of himself that weren’t sexual. At least twice, he also showed her photos that included Cooper. She said he would sometimes brag about his son and how smart the boy was.

“He would never do anything to hurt his baby?” Kilgore asked.

“No, definitely not,” the young woman replied.

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